Formed inflatable cellular cushioning article and method of making same

ABSTRACT

An inflatable article has a first film bonded to a second film so as to provide between the first film and the second film a plurality of inflatable chambers, each of the inflatable chambers containing a plurality of cells. Each of the cells is connected to at least one adjacent cell by an inflatable connecting channel. The first film is bonded to the second film between adjacent inflatable chambers. The first film and the second film each have at least one formed region corresponding with a location of a cell, with the at least one formed region of the second film being nested into the at least one formed region of the first film. Also disclosed are processes of making the inflatable article.

FIELD OF THE INVENTION

The invention pertains to cellular cushioning articles, especially aircellular cushioning articles suitable for packaging end use.

BACKGROUND OF THE INVENTION

Air cellular cushioning articles suitable for packaging applicationshave been in commercial use for several decades. One of the products inwidespread commercial use is BubbleWrap® cellular cushioning, oneembodiment of which is made using heat and vacuum to form spaced-apartair-filled cavities in a first film and thereafter heat sealing a flat“backing” second film to the flats between the cavities of the firstfilm, so that air is entrapped in each of the formed cavities making upthe individualized cells. The resulting air-cellular cushioning productcomprises discrete closed bubbles. If any one bubble deflates, no otherbubble necessarily deflates. One significant disadvantage of BubbleWrap®cellular cushioning is that shipping costs are high per unit weight ofproduct because the product density is low, i.e., the shipping of suchproducts is mostly shipping air.

Although Bubble Wrap® cellular cushioning products have not beensignificantly displaced by inflatable flexible cushioning articles, inthe past there have been a number of commercialized air-cellularcushioning products for packaging which have been designed to beinflated by the end user, i.e., inflated and sealed shut immediatelybefore end use by the packager. These products offer the advantage ofbeing shippable before inflation, providing for much more efficienttransport and storage before use, as any given volume within a truck orwarehouse can hold over thirty times as much product (on a weight basis)if it is uninflated rather than shipped to the packager while inflated.

Flat films which are sealed together to make an inflatable cellularcushioning product exhibit a disadvantage of widthwise contraction uponinflation. One way to reduce widthwise contraction upon inflation is tothermoform one of the films as disclosed in U.S. Pat. No. 6,423,166, toSimhaee. However, this product exhibits the disadvantage of having toremove entrapped air from the volume between the bubble sheet and thebase layer, in order to achieve a higher density product which providesthe advantage of more efficient transport and storage.

It would be advantageous to provide a cellular cushioning article havingthe density advantage of an uninflated, inflatable product withouthaving to remove air from within the cells. The removal of air is aprocess step which is time-consuming and difficult to carry out,especially to the degree of substantially complete removal, or completeremoval, of the air from between the two films.

SUMMARY OF THE INVENTION

The present invention pertains to an inflatable flexible cellularcushioning article made from two films sealed together in a patternproviding a plurality of inflatable chambers. At least some of thechambers (preferably all of the chambers) include a plurality ofinflatable cells connected to one another by connecting channels. Bothof the films have formed regions which allow the article to undergoinflation with reduced lateral contraction relative to the inflation ofunformed films which have been sealed together to make an inflatablecellular cushioning article. Because the formed regions of the secondfilm are nested into the formed regions of the first film, both filmsare formed and there is no need to remove air from between the films inorder to reduce the volume occupied by the formed inflatable article.Upon inflation of the article, the formed regions of the second filminvert and separate from the formed regions of the first film. Relativeto an unformed inflatable article, the formed regions impart increasedcell height and increased cell volume, relative to an inflatable articlemade from unformed films.

As a first aspect, the present invention is directed to an inflatablecellular cushioning article comprising a first film bonded to a secondfilm so as to provide between the first film and the second film aplurality of inflatable chambers. Each of the inflatable chamberscomprises a plurality of cells. Each of the cells of the same chamber(i.e., of any given chamber) is connected to at least one adjacent cellby an inflatable connecting channel. The first film is bonded to thesecond film between adjacent inflatable chambers. The first film and thesecond film each have at least one formed region corresponding with alocation of a cell, with the at least one formed region of the secondfilm being nested into the at least one formed region of the first film.Optionally, the regions of the films which are to serve as theconnecting channels can also be formed.

Preferably, the first film and the second film each have a plurality offormed regions, each of the formed regions corresponding with thelocation of a cell, with each of the formed regions of the second filmbeing nested into each of the formed regions of the first film.

Preferably, each of the formed regions of the first and second films issurrounded by an unformed, unbonded region of the film for enveloping asingle inflatable cell. This unbonded region is preferably narrow, i.e.,is from 0.2 mm to 6 mm, more preferably from 1 mm to 3 mm.

Preferably, the inflatable chambers extend transversely across theinflatable article. That is, the inflatable chambers extend in adirection which is either perpendicular to the machine direction of theinflatable article, or is within 45 degrees of a line which istransverse to the machine direction of the inflatable article.

The first film can be bonded to the second film with an adhesive, acohesive, or a heat seal. If an adhesive is used instead of heatsealing, an ultraviolet-curable adhesive is a preferred adhesive forbonding the first film to the second film.

In one preferred embodiment, the film(s) each have a unit weight of from20 to 70 grams per square meter, and each of the formed regions in thefilm(s) each have a maximum dimension of from 0.25 to 3 inches. Inanother preferred embodiment, the film(s) each have a unit weight offrom 60 to 250 grams per square meter, and each of the formed regions inthe first film and the second film have a maximum dimension of from 0.5to 6 inches.

Preferably, each of the formed regions of the film(s) have a height offrom about 1 millimeter to about 50 millimeters. As used herein, thephrase “height of the formed region” refers to the maximum deviation ofany one formed region from the plane of the unformed portion of thefilm, i.e., the plane containing the land area of the film. Of course,different formed regions can have different heights. More preferably,the formed regions of the film have a height of from 2 to 25millimeters, more preferably from 5 to 15 millimeters.

Preferably, each of the film(s) have a thickness of from about 0.5 toabout 6 mils; more preferably, from 1 to 3 mils.

In one embodiment of the present invention, the inflatable article hasan open inflation skirt along a first edge running the length of theinflatable article.

In another embodiment, the inflatable article has a closed inflationmanifold running the length of the inflatable article. In a firstspecies of this alternative embodiment, the closed inflation manifoldextends along a first side edge extending the length of the inflatablearticle, with the plurality of inflatable chambers extending from theinflation manifold across the inflatable article and towards the otherside edge extending the length of the inflatable article. In a secondspecies of this alternative embodiment, a plurality of inflatablechambers extends from a first side of the inflation manifold and aplurality of inflatable chambers extends from a second side of theinflation manifold, with the inflatable chambers which extend from thefirst side of the inflation manifold extending across the inflatablearticle towards the first side edge of the inflatable article, and theinflatable chambers which extend from the second side of the inflationmanifold extending across the inflatable article towards the second sideedge of the inflatable article. In this second species, the closedinflation manifold is not located along one side edge of the article,but instead extends down an interior portion of the article. In oneembodiment, the inflation manifold is centered on a longitudinal (i.e.,machine direction) centerline of the article.

Preferably, each of the inflatable chambers contains from 1 to 100cells, more preferably 2 to 50 cells, 3 to 20 cells, or 4 to 10 cells.

In one embodiment, the first and second films are connected to oneanother along one fold line. In another embodiment the first and secondfilms are connected to one another along two fold lines. In anotherembodiment, the first film and second film are separate films. Inanother embodiment, the bond is a heat seal.

The first film and/or the second film can be a monolayer film or amultilayer film. Preferably the first film and/or the second filmcomprises at least one member selected from the group consisting ofpolyethylene, ethylene/alpha-olefin copolymer, ethylene/unsaturatedester copolymer, ethylene/unsaturated acid copolymer, polypropylene,propylene/ethylene copolymer, polyethylene terephthalate, polyamide,polyvinylidene chloride, polyacrylonitrile, ethylene/vinyl alcohol(i.e., EVOH, which is actually the saponified ester of ethylene/vinylacetate copolymer), and propylene/vinyl alcohol (i.e., PVOH).Preferably, the first film is a multilayer film and the second film is amultilayer film.

Preferably, the first film comprises a seal layer and an O₂-barrierlayer, and the second film comprises a seal layer and an O₂-barrierlayer. While the first film and/or the second film may further comprisea tie layer between the seal layer and the O₂-barrier layer, the polymerwhich serves to tie the seal layer to the O₂-barrier layer mayalternatively be blended into either the O₂-barrier layer or the seallayer, in order to avoid providing the film with a separate seal layer.However, it is preferred that the first film and the second film eachcomprise the seal layer, the O₂-barrier layer, and a tie layer betweenthe seal layer and the O₂-barrier layer, with the seal layer of thefirst film being bonded to the seal layer of the second film in theinflatable article. The seal layer of the first and second filmscomprises at least one member selected from the group consistinghomogeneous ethylene/alpha-olefin copolymer, very low densitypolyethylene, low density polyethylene, linear low density polyethylene,ethylene/unsaturated acid copolymer (particularly ethylene/vinyl acteatecopolymer), ethylene/unsaturated ester copolymer, and ionomer resin.

Preferably, the first film comprises first and second outer layers, acentral gas barrier layer, a first tie layer between the first outerlayer and the gas barrier layer, and a second tie layer between the gasbarrier layer and the second outer layer. Preferably, the second filmcomprises first and second outer layers, a central gas barrier layer, afirst tie layer between the first outer layer and the gas barrier layer,and a second tie layer between the gas barrier layer and the secondouter layer. Preferably, the first outer layer of the first film issealed to the first outer layer of the second film. Preferably, thefirst and second outer layers of the first film have the same layerthickness and have the same polymeric composition, and the first andsecond tie layers of the first film have the same layer thickness andthe same polymeric composition, and the first and second outer layers ofthe second film have the same layer thickness and have the samepolymeric composition, and the first and second tie layers of the secondfilm have the same layer thickness and the same polymeric composition.Preferably, the gas barrier layer of the first and/or second filmscomprises at least one member selected from the group consisting ofpolyamide, hydrolyzed ethylene/vinyl acetate copolymer, polyvinylidenechloride, polyacrylonitrile, and polyester, and the gas barrier layer ofthe second film comprises at least one member selected from the groupconsisting of polyamide, hydrolyzed ethylene/vinyl acetate copolymer,polyvinylidene chloride, polyacrylonitrile, and polyester.

As a second aspect, the present invention is directed to a process formaking an inflatable article, comprising: (A) bonding a portion of afirst film to a corresponding portion of a second film so that aresulting sealed article comprises a plurality of inflatable chamberscomprising a plurality of inflatable cells, each of the cells in thechambers being connected to an adjacent cell by an inflatable connectingchannel, the first film being bonded to the second film between adjacentinflatable chambers; and (B) forming at least one region of the firstfilm and at least one region of the second film, the formed regionscorresponding with a location of a particular cell, with the formedregion of the second film being nested into the formed region of thefirst film. Optionally, the process can further comprise extruding thefirst and second films and thereafter cooling the first and second filmsbefore bonding the first film to the second film.

Preferably, the process is an integrated process, in that the extrusion,bonding, and forming are carried out in an uninterrupted, continuousprocess. In a non-integrated process, an intermediate product isproduced and placed aside awaiting further processing in one or morefurther processing steps. If an intermediate product is maintained inthe production line, but is held in a moving inventory environment on aracking system, with the process being completed without separation ofthe film strand being extruded, the process is considered to be anintegrated process.

Optionally, after the inflatable article is made, it can be pressed intoa flatter configuration by a pressing means. That is, the formed regionsof the article can be pressed into a configuration in closer alignmentwith the plane of the unformed areas of the article, so that uponwinding the inflatable article into a roll, a wound roll of greaterdensity can be produced. Means for pressing the article into the flatterconfiguration include nip rollers, oscillating flat plate press, etc.

In one embodiment, the first film and second film are extruded asseparate films, either through separate slot dies or through separateannular dies. If through separate annular dies, the resulting filmtubings can either be self welded in lay-flat configuration to form twoflat films, or each can be slit lengthwise and bonded to one anotherwhile each is in its lay-flat configuration.

In another embodiment, the extrusion is carried out through a slot die,with the resulting film being folded to form the first and second filmswhich are connected to one another along one fold line.

In another embodiment, the extrusion is carried out through an annulardie to form a tubular film which is collapsed into lay-flatconfiguration and slit lengthwise to form the first and second filmswhich are connected to one another along one fold line.

In another embodiment, the extrusion is carried out through an annulardie to form a tubular film which is collapsed into lay-flatconfiguration, to form first and second films which are connected to oneanother along two fold lines.

In one preferred embodiment, the bonding of the first film to the secondfilm is carried out by passing the second film between a heat sealingroller and the first film, with both the first film and the second filmmaking a partial wrap together around the sealing roller, with thesecond film making a longer partial wrap around the sealing roller thanthe first film, with the first film contacting the second film after thesecond film has made a portion of its partial wrap around the sealingroller. Preferably, the process further comprises contacting the firstfilm with a nip roller while the first and second films are making thepartial wrap together around the heat sealing roller, the nip rollerpressing the first and second films together to assist in heat sealingthe first film to the second film.

In one embodiment, the forming of the first and second films is carriedout by passing the first and second films together between: (i) anembossing roller having a plurality of cavities on the surface thereof;and (ii) a forming roller having a plurality of protuberances on thesurface thereof. The forming roller has a surface temperature low enoughto prevent the first and second films from fusing to one another in thearea being formed. The protuberances on the forming roller are alignedto enter the cavities of the embossing roller between the embossingroller and the forming roller, with the protuberances being undersizedrelative to the cavities of the embossing rollers so that portions ofthe first film which the protuberances force into the cavities in theembossing roller are not fused to the second film. Preferably, theforming roller and the embossing roller are in nip relationship with oneanother.

In one preferred embodiment, the embossing roller has an outer surfacewhich has a temperature above ambient temperature. The temperature ofthe embossing roller can even be high enough to cause the first andsecond films to bond to one another throughout the land areas, i.e., theareas in which the first film or second film contacts the embossingroller. However, the process should not cause the first and second filmsto bond to one another in the area in which the first and/or secondfilms are being formed. Thus, the temperature of the forming rollershould be low enough that the first and second films do not bond to oneanother in the regions in which the first and/or second films contactthe forming roller. In another preferred embodiment, the embossingroller has an outer surface at ambient temperature (i.e., roomtemperature), or below ambient temperature, with the forming being done“cold”, i.e., without heating either of the films to a temperature atwhich bonding to one another occurs.

In one embodiment, the bonding step is carried out before the formingstep. In an alternative embodiment, the forming step is carried outbefore the bonding step. In yet another embodiment, the bonding step andthe forming step are carried out simultaneously using a rotatable,heated sealing roller having an outer surface, the outer surface of thesealing roller comprising a first surface portion defining aconfiguration corresponding to a desired heat seal pattern and formed ofa first material having a first thermal conductivity and a secondsurface portion formed of a second material having a second thermalconductivity lower, and preferably substantially lower, than the firstthermal conductivity such that only areas of the film in contact withthe first surface portion are heat sealed together while areas of thefilm contacted by the second surface portion remain unsealed to eachother. Such a sealing roller is described in U.S. Ser. No. (10/980,754),filed Nov. 3, 2004, in the name of Robert O'Dowd, entitled “PROCESS ANDAPPARATUS FOR MAKING HEAT-SEALED ARTICLES”, the entirety of which ishereby incorporated by reference thereto.

In one embodiment, both the first and second films are formed in aplurality of regions, each of the regions corresponding with at leasttwo adjacent cells of the same chamber, and at least one connectingchannel connecting the two adjacent cells. Preferably, the formed regionis continuous throughout the inflatable chamber, and the unformed regionis continuous throughout the unformed region (i.e., land area). Withthis arrangement of formed and unformed regions, a smooth heat sealingroller can thereafter be used to heat seal the two films together in theunformed regions between the inflatable chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective cut-away view of an inflatable articlein accordance with the present invention, before inflation.

FIG. 1A illustrates a top view of the inflatable article of FIG. 1,except that the inflatable article is not exploded in the top view ofFIG. 1A.

FIG. 2 is a cross-sectional view taken through section 2-2 of FIG. 1,except that the cross-sectional view is of the inflatable articleunexploded.

FIG. 3 is an exploded perspective cut-away view of the inflatablearticle of FIG. 1, after inflation.

FIG. 4 is a cross-sectional view taken through section 4-4 of FIG. 3,except that this cross-sectional view is of the inflatable articleunexploded.

FIG. 5 is a perspective cut-away view of a first alternative inflatablearticle in accordance with the present invention, after inflation.

FIG. 6 is a perspective cut-away view of a second alternative inflatablearticle in accordance with the present invention, after inflation.

FIG. 7 is a schematic of a first process for making the inflatablearticle in accordance with the present invention.

FIG. 8 is a schematic of an alternative process for making theinflatable article in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “film” is used in a generic sense to includeplastic web, regardless of whether it is film or sheet. Preferably,films of and used in the present invention have a thickness of 0.25 mmor less.

As used herein, the phrases “first film” and “second film” include notjust a first film which is discrete from (i.e., separated from) a secondfilm, but also a first film which is a first leaf of a folded film(e.g., a centerfolded film) with the second film being the second leafof the folded film. Still further, the first film could be a firstlay-flat side of a lay-flat film tubing, and the second film could be asecond lay-flat side of the same film tubing, with both lay-flat sidesbeing joined to each other along two fold lines.

As used herein, the phrase “flat film” is used with respect to a filmwhich is in the form of a sheet, i.e., has side edges which form thefilm boundaries along its length. A flat film is to be contrasted withan annular film, which in lay flat position has no side “edges”, butrather has side folds (which optionally may be creased) along the lengthof the film tubing.

As used herein, the phrase “inflatable chamber” refers to a contiguousvolume between two films bonded together to form an uninflated,inflatable article. The inflatable article of the present invention hasa plurality of inflatable chambers. While the two films are preferablybonded to one another throughout the area between adjacent chambers, itis only necessary to bond the two films together along the perimeter ofthe inflatable chamber, so that upon sealing off the inflation channelafter the chamber has been inflated, the inflation gas is retainedwithin the chamber. The volume within the chamber is increased byintroduction of inflation gas, which causes the two films to separatefrom one another to form an inflated chamber. Each inflated chamberpreferably comprises a plurality of inflatable cells and a plurality ofchannels, including an inflation channel and at least one connectingchannel. The phrase “inflatable cell”, as used herein, refers to anenlarged region of an inflatable chamber. The phrase “inflation channel”refers to an inflatable passageway in a region of the inflatable articlethrough which the inflation fluid can be pumped to fill an inflatablechamber. The phrase “connecting channel” refers to an inflatablepassageway in a region of an inflatable chamber through which theinflation fluid can be pumped from one cell to another.

Because the inflatable article has inflatable chambers designed for useas cellular cushioning, each chamber is to be inflated with a gas. Airis the preferred gas for inflation. Other suitable gases includenitrogen, carbon dioxide, argon, and helium, as well as mixtures ofthese gases.

As used herein, the phrase “formed region” refers to a region of a filmwhich extends out of the plane of the film. For example, each of the“bubbles” in the thermoformed film portion of Bubble Wrap® cellularcushioning is a formed region. Forming is a process in which the shapeof the film is changed to a desired configuration, usually with the aidof heat and pressure to produce a non-elastic deformation of the film,thereby increasing the surface area of the film and the shape of thefilm. However, as used herein, the “forming” of a film, and theresulting “formed regions” in the film, include molding and castingprocesses, and the resulting articles, respectively. Preferably, theformed article of the present invention is made by thermoforming or coldforming of two flexible film sheets which have been bonded to oneanother before forming, or which are bonded to one another after theforming process is carried out.

The phrase “maximum dimension”, as used with respect to formed regionsof films, refers to the largest measured dimension of the formed regiontaken in any of the following: (a) the main plane of the film, and (b)in any plane parallel to the main plane of the film, and (c) any planeperpendicular to the main plane of the film.

As used herein, the term “nested” refers to the relationship in which atleast a portion of the formed region of a second film resides within atleast a portion of a cavity of the formed region of a first film.Nesting is present if any portion of the formed region of the secondfilm breaks the plane across the base of the formed region of the firstfilm. Nesting is maximized if the second film contacts the first filmthroughout the cavity of the first film.

As used herein, the phrase “a formed region corresponding with alocation of a cell” is inclusive of (a) formed regions limited to asingle cell, e.g., a formed film portion which is surrounded by anunformed, unbonded film portion of a single cell, as well as (b) formedregions which extend to or even through one or more boundaries betweenone or more unbonded portions of the film and one or more bondedportions of the films. Thus, any given formed region can include part orall of that portion of the films which envelops one or more cells of oneor more inflatable chambers. Preferably, however, the inflatable articleincludes a plurality of formed regions, with each formed region beingconfined to an unbonded portion corresponding with a single cell.

As used herein, the term “seal” refers to any seal of a first region ofa film surface to a second region of a film surface. The first andsecond regions can be on the same or different films. The seal ispreferably formed by the use of heat and pressure. In making the seal,at least one region (preferably both regions) is heated to its sealinitiation temperature. The sealing can be performed by any one or moreof a wide variety of manners. Peferably sealing is carried out bycontacting the films with a heated drum to produce a heat seal, asdescribed below. The term “seal” is also inclusive of a film adhered toitself with an adhesive or cohesive, or films adhered to one anotherwith an adhesive or cohesive. However, the various layers of amultilayer coextruded film are not considered to be “sealed” to oneanother because the term “seal”, as used herein, refers to adhering lessthan the entire film surfaces to one another. Thus, a seal leaves anunsealed region of the film.

In contrast, the bond holding coextruded entire film layers to oneanother is herein termed a “lamination”. The term “lamination” isinclusive of not only layers coming together as molten streams, but alsolayers which are bonded to one another with an adhesive or cohesive.

The term “bond” is generic with respect to all manners of causing twofilms to cleave to one another, i.e., to adhere firmly to one another.Bonding is inclusive of being adhered to one another with adhesive,corona treatment, heat sealing, etc. Preferably, the two films arebonded by being heat sealed to one another.

Referring to FIG. 1, FIG. 1A, and FIG. 2 together, there is shown aninflatable article 10 that has not yet been inflated. Inflatable article10 has formed regions 16 in first film 12 and formed regions 18 insecond film 14. Films 12 and 14 are not bonded to one another in formedregions 16 and 18. Formed regions 18 in second film 14 are nested withinthe respective cavities of formed regions 16 of first film 12.

First film 12 and second film 14 are sealed together in bonded region21. The edges of bonded region 21 are shaped, sized, and located todefine each of the inflatable chambers of inflatable article 10 as wellas the inflation fluid entrance ports 22 and inflation channels 26. Theentire shaded region in FIG. 1A corresponds with the bonded region 21between first film 12 and second film 14.

Each of the inflatable chambers of inflatable article 10 includesinflatable inflation channel 26, a plurality of inflatable cells 24, anda plurality of inflatable connecting channels 28. The regions of films12 and 14 which make up inflation channels 26 and connecting channels 28may be flat, i.e., unformed, as illustrated in FIGS. 1, 1A, and 2, ormay be formed and nested with one another, i.e., in a manner notillustrated but corresponding with the nesting of formed regions 16 and18. Inflation channels 26 extend from open skirt 30 formed by unbondedfilm side edge regions 32 and 34.

Bonded region 21 between adjacent inflatable chambers are actually onecontinuous sealed region, as bonded region 21 extends continuously alongthe length of longitudinal edge 35. See FIG. 1A. The portions of bondedregion 21 which are between adjacent inflatable chambers, in combinationwith that portion of bonded region 21 along longitudinal edge 35, definethe boundaries of each inflatable chamber. As can be seen in FIGS. 1 and1A, bonded region 21 has a repeating pattern. Bonded region 21 ispreferably made using heat and pressure to cause a bond between theinner surfaces of films 12 and 14. Alternatively, films 12 and 14 may beadhesively bonded to each other.

FIG. 3 is an exploded perspective cutaway view of inflated article 11with each inflatable chamber heat sealed closed with heat seal 38. Heatseal 38 extends along the length of inflated article 11, providing aseal across each of inflation channels 26. Unbonded side edge regions 32and 34 serve as flanges and together form open skirt 30 used by theinflation apparatus (not illustrated) during the inflation process.Inflated cells 24, inflated connecting channels 28, and those portionsof inflated inflation channels 26 which are downstream (relative to theflow of the inflation gas) of heat seal 38, together become a singleinflated chamber, with the resulting inflated cells 24 being connectedin series and in fluid communication with one another, by inflatedconnecting channels 28.

In each inflated chamber, inflated cells 24 are illustrated arranged inseries, with inflated cells 24 of a chamber extending from proximateinflated cell 40, i.e., the first cell in the series, which is the cellclosest to inflation channel 26, to distal inflated cell 41, which isthe terminal cell in each inflated chamber. Each chamber has apredetermined length, with the length of each chamber being the same ordifferent. As illustrated in the embodiments of FIG. 1 and FIG. 3, thelength of adjacent chambers alternates in an “A-B-A-B . . . ”arrangement, with each of the “A” chambers having the same length andeach of the “B” chambers having the same length. Moreover, inflatablecells 24 in adjacent chambers are staggered, i.e., off-set from oneanother, in order that the cells in adjacent chambers are in aclose-packed arrangement. The close-packing provides more cushioningvolume per unit area of inflatable article 10.

During inflation of each inflatable chamber, the formed region of secondfilm 14 inverts and separates from the formed region of first film 12.That this occurs can be seen by comparing FIG. 1 with FIG. 3, as thesetwo figures illustrate, respectively, the same inflatable article 10before inflation (i.e., FIG. 1) and after inflation (i.e., FIG. 3). Theinflation process forms an interior volume which expands upon theingress of inflation gas into the inflatable chambers.

The depth to which films 12 and 14 are formed may represent virtuallythe entire thickness of the inflated cells, or may represent only afraction of the thickness of the resulting inflated cells if both formedfilms bulge out to maximize the amount of inflation fluid between films12 and 14 from inflation of the chamber. The latter is illustrated inthe cross-sectional view of FIG. 4. Preferably, first film 12 and secondfilm 14 are each formed to a depth of from about 1 to about 50millimeters, more preferably from about 2 to about 25 millimeters, andmore preferably from about 5 to about 15 millimeters. As illustrated inthe particular embodiment of FIG. 4, upon inflation the formed regionsof second film 14 invert and the resulting inflated chambers bulge fromthe inflation fluid, resulting in a maximum thickness which is greaterthan twice the formed depth of first film 12 and second film 14.

The inner unbonded surfaces of side edge regions 32 and 34 can bebrought into close slidable engagement with outwardly facing surfaces ofan appropriately configured nozzle or other inflation means so as toprovide a partially-closed inflation zone which promotes efficient andreliable sequential inflation of the inflatable chambers, withoutrestricting the movement of the web or inflation nozzle that is requiredto effect this sequential inflation. Unbonded side edge regions 32 and34, which together form the open skirt, are preferably at least ¼ inchto 3 inches in width and, more preferably, from ½ inch to 1½ inches inwidth. Unbonded side edge regions 32 and 34 may have different widths;alternatively, they may have the same width, as in the embodimentillustrated in FIG. 1. A preferred apparatus and method for effectinginflation and sealing of the chambers is disclosed in U.S. Ser. No.10/057,067, Pub. No. 2002/0166788A1, published Nov. 14, 2002, to Sperryet. al., entitled “APPARATUS AND METHOD FOR FORMING INFLATED CHAMBERS”,which is hereby incorporated, in its entirety, by reference thereto.

Once inflatable article 10 is inflated, inflated connecting channels 28serve as flexible junctions, allowing the inflated article 11 to bereadily bent so it can be conformed about a product, providing optimalcushioning. In another embodiment, the seal pattern can compriserelatively narrow seals that do not provide planar regions. These sealsserve as the common boundary between adjacent chambers. Such a sealpattern is shown for example in U.S. Pat. No. 4,551,379, the disclosureof which is incorporated herein by reference.

FIG. 5 is a perspective cut-away view of alternative inflated article 50in accordance with the present invention. Inflated article 50 is thesame as inflated article 11 illustrated in FIG. 3, except that insteadof having the unbonded edge regions 32 and 34 which form an open skirtas in the embodiment of FIG. 3, inflated article 50 has longitudinalseal 37 running the length of the edge along inflation channels 22,forming inflation manifold 52 which provides a closed channel forinflation of the inflatable chambers.

FIG. 6 is a perspective cut-away view of a second alternative inflatedarticle 54 in accordance with the present invention. The embodiment ofFIG. 6 differs from the embodiment of FIG. 5 in that it has aninternally-located inflation manifold 56 having inflatable chambersextending from opposing sides of inflation manifold 56. Although article54 is illustrated as inflated, it would be provided with a longitudinalseal (not illustrated) along each side of inflation manifold 56, to sealeach of the inflated chambers closed.

FIG. 7 is a schematic of a process for making the inflatable article ofthe present invention. In FIG. 7, extruders 62 and 64 extrude first flatfilm 120 through a first slot die, and second flat film 140 through asecond slot die, respectively. After extrusion, film 120 makes a partialwrap around heat transfer (cooling) roller 66, which preferably has adiameter of 8 inches and which is maintained at a surface temperaturewell beneath the fusion temperature of the extrudate, e.g., from100-150° F. Second film 140 makes partial wraps around each of heattransfer (cooling) rollers 68 and 70, each of which has a diameter of 8inches and each of which is maintained at a surface temperature similarto that of cooling roller 66. After cooling, first film 120 makes apartial wrap (about 90 degrees) around Teflon® coated rubber nip roll72, which has a diameter of 8 inches and which has, as its primaryfunction, maintaining nip with heat transfer (heating) raised surfaceroll 76. While first film 120 is making a partial wrap around nip roll72, second film 140 merges with first film 120, with films 120 and 140being together in partial wrap for a short distance around nip roll 72before together entering first nip 74. Nip roller 72 provides a locationfor films 120 and 140 to come together without being marred ordistorted.

Thereafter, second film 140 makes direct contact with raised surfaceroller 76 (which is illustrated as a smooth roll only for simplicity ofillustration). First nip 74 subjects films 120 and 140 to a pressure offrom 2 to 10 pounds per linear inch, preferably 2 to 6 pounds per linearinch, more preferably about 4 pounds per linear inch.

Films 120 and 140 together contact raised surface roller 76 for adistance of about 180 degrees. Raised surface roller 76 has a diameterof 12 inches, and is heated by circulating hot oil therethrough so thatthe roller surface is maintained at a temperature of from 280° F. to350° F. The edges of the raised surface on roller 76 are rounded over toa radius of 1/64 inch. Raised surface roller 76 also has a Teflon®polytetrafluoroethylene coating thereon, with the raised surfaces beingabove the background by a distance of ¼ inch (0.64 cm). Moreover, theraised surface is provided with a surface roughness of from 50 to 500root mean square (i.e., “rms”), preferably 100 to 300 rms, morepreferably about 250 rms. This degree of roughness improves the releasequalities of raised surface roller 76, enabling faster process speedsand a high quality product which is undamaged by licking back on raisedsurface roller 76.

The raised surface heats that portion of film 140 which contacts theraised surface of roller 76. Heat is transferred from raised surfaceroller 76, through a heated portion of film 140, to heat a correspondingportion of film 120 to be bonded to film 140 to produce, for example,bonded region 21 of inflatable article 10 illustrated in FIG. 1. Uponpassing about 180 degrees around raised surface roller 76, heated films120 and 140 together pass through second nip 78, which subjects heatedfilms 120 and 140 to about the same pressure as is exerted in first nip74, resulting in a bonded region between films 120 and 140. The bondedregion has a repeating pattern.

After passing through second nip 78, films 120 and 140, now bondedtogether, pass about 90 degrees around heat transfer (cooling) roller80, which has a diameter of 12 inches and which has cooling waterpassing therethrough, the cooling water having a temperature of from100° F. to 150° F. Cooling roller 80 has a ¼ inch thick (about 0.64 cmthick) release and heat-transfer coating thereon. The coating is madefrom a composition designated “SA-B4”, which is provided and applied toa metal roller by Silicone Products and Technologies Inc of Lancaster,N.Y. The coating contains silicone rubber to provide cooling roller 74with a Shore A hardness of from 40 to 100, preferably 50-80, morepreferably 50-70, and still more preferably about 60. The SA-B4composition also contains one or more fillers to increase the heatconductivity to improve the ability of cooling roller 80 to cool thebonded region of the films. Various additional details of the apparatusand process of FIG. 7 are set forth in U.S. Pat. No. 6,800,162 B2 toKannankeril et al., entitled INTEGRATED PROCESS FOR MAKING INFLATABLEARTICLE, issued Oct. 5, 2004, which is hereby incorporated, in itsentirety, by reference thereto. Inflatable article 100 thereafter passesthrough a forming apparatus 84 (illustrated schematically in FIG. 7),which uses pressure alone, or a combination of heat and pressure, toform a plurality of locations on inflatable article 100, to result inuninflated, inflatable article 10 as illustrated in FIG. 1. Of course,forming apparatus 84 should not heat the unbonded regions of inflatablearticle 100 to a temperature high enough that the unbonded regions fuseto one another.

As an alternative to the process illustrated in FIG. 7, described above,the film for the entire article may be formed by extruding a single flatfilm (i.e., instead of two films 12 and 14) from a slot die having atleast twice the desired width of the inflatable article, this film beingcenter folded and bonded to itself to form the inflatable article. As isreadily apparent, depending upon the manner in which the centerfoldedfilm is bonded together, the resulting inflatable article can utilize anopen inflation skirt or a closed inflation manifold.

Alternatively, a tubular film can be extruded through a single annulardie, in a process producing a film having a circumference equal to twicethe desired width of the inflatable article. In one embodiment, thistubular film is placed in lay flat configuration without anylongitudinal slitting, with the inside of the tubing being bonded toitself to result in an inflatable article having a closed inflationmanifold. Alternatively, the tubular film can be slit lengthwise,centerfolded in lay-flat configuration, and bonded to itself to form theinflatable article. Again, depending upon the manner in which thebonding is performed, the resulting inflatable article can have eitheran open inflation skirt or a closed inflation manifold.

FIG. 8 is a schematic of an alternative process for making an inflatablearticle in accordance with the present invention. FIG. 8 illustrates aprocess in which flat films 121 and 141 are extruded from respectiveextruders 63 and 65, each of which have a slot die therewith, followingwhich films 121 and 141 each make a partial wrap around heat transfer(cooling) rollers 67 and 69, respectively. Flat films 121 and 141 areforwarded off of respective cooling rollers 67 and 69 and come togetheron merging and alignment roller 73, with merged films 121 and 141passing through a nip between embossing roller 75 and forming roller 85.

Embossing roller 75 has a plurality of cavities 77 on the surfacethereof corresponding with the location of each of the cells of theinflatable chambers, as well as elongate-shaped cavities (notillustrated) corresponding to connecting channels and inflationchannels, and circumferential channel 79 (optional) corresponding withthe location of the inflation manifold (optional). Forming roller 85 hasa plurality of annular-shaped protuberances 87 corresponding with thelocation of each of the cells of the inflatable chambers, as well as anelongate-shaped protuberances (not illustrated) corresponding to theconnecting channels and inflation channels, and circumferentialprotuberance 89 corresponding with the location of the optionalinflation manifold. Embossing roller 75 and forming roller 85 worktogether to form films 121 and 141 as they pass through nip 83.Embossing roller 75 and forming roller 85 use pressure and/or vacuum,preferably in combination with heat, to form films 121 and 141.

Regions of film 121 are formed so that they nest within the cavitiesformed in film 141. If heat is used in the forming operation, thetemperature to which films 121 and 142 are heated should be below thetemperature at which films 121 and 141 fuse together under the appliedpressure in the nip. The forming which occurs in nip 83 transforms flatfilms 121 and 141 so that they emerge from nip 83 as first formed film123 and second formed film 143.

Of course, protuberances 87 and 89 on forming roller 85 are sized,positioned, and aligned to enter cavities 77 and 79 on embossing roller75, in nip 83 between embossing roller 75 and forming roller 85.Protuberances 87 and 89 are undersized relative to cavities 77 and 79 onembossing roller 75. In the forming process, flat films 121 and 141 areformed, but not damaged, as they pass together through nip 83, at whichprotuberances 87 and 89 force regions of films 121 and 141 into cavities77 and 79, with pressure alone or with a combination of heat andpressure. Heat can be supplied by heating at least the film-contactsurface of embossing roller 75 and/or forming roller 85. In order toassist in the forming process, any heating which is used should heat thefilms to a temperature below which films 121 and 141 bond to oneanother, but above the glass transition temperature (“T_(g)”) of one ormore of the polymers in one or more of films 121 and 141. Apparatus forheating films 121 and 141 to an elevated temperature is not illustratedin FIG. 8.

After emerging from nip 83, the resulting formed films 123 and 143 makea partial wrap together around heat sealing roller 95. Formed films 121and 141 contact heat sealing roller 95 so that only the unformed area(i.e., “land area”) of formed film 121 is in direct contact with the hotsurface of heat sealing roller 95. As illustrated in FIG. 8, the formedregions of formed films 123 and 143 are oriented away from heat sealingroller 95, so that the formed areas are not bonded to one another. Thetension on formed films 123 and 143 presses the land areas of formedfilms 121 and 141 against each other, and together with the heat fromheat sealing roller 95 for the period of the partial wrap around hotsealing roller 95, causes formed films 121 and 141 to be heat sealed toone another at the land area (i.e., the unformed area), while leavingthe formed areas unsealed to one another, to result in an uninflatedformed inflatable article, such as inflatable article 10 illustrated inFIG. 1.

As an additional (and optional) step in the process illustrated in FIG.6, uninflated formed inflatable article 10 can be run through anadditional nip to mash the formed region of the films flat. This assistsin winding up uninflated formed inflatable article 11, in that theformed areas, once flattened, are less destabilizing to the roll than ifthe inflatable article 10 is wound up in its formed but unflattenedstate.

Although embossing roller 75 as illustrated has cavities 77 which extendinwardly from a smooth cylindrical surface, embossing roller 75 could beprovided with multiple flat surfaces each extending across roller 75,with cavities 77 extending inwardly from a given flat surface. Forexample, roller could have a hexagonal cross-sectional shape with eachof the six cavities 77 being positioned in the middle of a side of thehexagon. Likewise, forming roller 85 could have a hexagonalcross-sectional shape with each of the six protrusions 87 extending fromthe middle of a side of the hexagon. Providing such a “faceted” designto the embossing and forming devices could be used in the process ofFIG. 8, as well as in the process of FIG. 7, i.e., substituting forforming apparatus 84. Each roller could be provide with from 3-100facets, more preferably from 6 to 50 facets, more preferably from 12 to50 facets, and more preferably from 20 to 50 facets.

A significant difference between the process of FIG. 7 and the processof FIG. 8 is that in the process of FIG. 7, the inflatable article ismade by first heat sealing the films to one another, and thereafterforming the films. In contrast, in the process of FIG. 8, the films arefirst formed and thereafter heat sealed to one another.

Further details concerning methods making inflatable article 10 aredisclosed below and are also disclosed in U.S. Pat. No. 6,800,162 B2.Still further details are disclosed in several additional copending U.S.patent applications, including (i) U.S. Ser. No. 10/302004, entitled“HIGH STRENGTH HIGH GAS BARRIER CELLULAR CUSHIONING ARTICLE”, toKannankeril et al., filed Nov. 22, 2002, published as 2004/0101658A1,(ii) U.S. Ser. No. 10/648113 entitled “HIGH STRENGTH HIGH GAS BARRIERCELLULAR CUSHIONING ARTICLE”, to Kannankeril et al., filed Aug. 26,2003, published as 2004/0101659A1, and (iii) U.S. Ser. No. 10/648,015,entitled “PROCESS FOR MAKING AND AGING HIGH STRENGTH HIGH GAS BARRIERCELLULAR CUSHIONING ARTICLE”, to Kannankeril et al., filed Aug. 26,2003, published as 2004/0099986A1. The entirety of each of thesepublished applications is hereby incorporated by reference thereto.

The forming process utilized in FIG. 7 and FIG. 8 can be supplemented byproviding vacuum within the embossing roller 75 or 76. Vacuum can besupplied as described in, for example, U.S. Pat. No. 2,776,451, toChavannes, entitled “Apparatus and Method for Producing EmbossedThermoplastic Material”, issued Jan. 8, 1957, which is herebyincorporated, in its entirety, by reference thereto. See also U.S. Pat.No. 3,285,793, also to Chavannes, entitled “Method of Manufacturing aComposite Cellular Material”, issued 15 Nov. 1966, which is also herebyincorporated, in its entirety, by reference thereto. See also U.S. Pat.No. 3,346,438, also to Chavannes, entitled “Method and Apparatus forMaking Cushioning and Insulating Material”, issued Oct. 10, 1967, whichis also hereby incorporated, in its entirety, by reference thereto.

A preferred multilayer film structure for the film or films to be bondedtogether to make the inflatable cushioning article a symmetricalA/B/C/B/A layer arrangement having a total thickness of 1.5 mils. The Alayers together make up 86 percent of the total thickness (each layerhaving a thickness of 43%, as preferably the layer thickness is alsosymmetrical), each of the B layers making up 2% of the total thickness,and the C layer making up 10% of the total thickness. Each of the Alayers are made from a blend of 45% by weight HCX002 linear low densitypolyethylene having a density of 0.941 g/cc and a melt index of 4,obtained from Mobil, 45% by weight LF10218 low density polyethylenehaving a density of 0.918 g/cc and a melt index of 2, obtained fromNova, and 10% by weight SLX9103 metallocene-catalyzedethylene/alpha-olefin copolymer, obtained from Exxon. Each of the Blayers are tie layers made of 100% Plexar® PX3236 anhydride modifiedlinear low density polyethylene copolymer from Equistar Chemicals LP, ofHouston, Tex. The C layer is an O₂-barrier layer of 100% Caplon® B100WPpolyamide 6 having a viscosity of F_(av)=100, obtained from AlliedChemical.

Upon inflation, the cushioning article resists popping when pressure isapplied to a localized area because connecting channels 28 allow air tomove from one cell into another. The laminates show excellent creepresistance and cushioning properties due to inter-passage of air betweencells.

Preferably, the film(s) are as thin as possible, in order to minimizethe amount of resin used, but with the films being thick enough toprovide adequate durability. Preferably, the film(s) have a totalthickness of from about 0.1 to about 20 mils. More preferably, each filmhas a total thickness from about 0.5 to about 10 mils, more preferablyfrom about 0.8 to about 4 mils, and even more preferably from about 1.0to about 3 mils. Of course, the thickness may be somewhat reduced in theformed regions. The degree of thickness reduction depends upon theamount and manner in which the films are formed.

A dome-shaped formed region is a preferred shape for the film regionswhich are formed. The dome shape is preferred for the inflatable articleillustrated in FIGS. 1-6, and in the inflatable article made inaccordance with the processes illustrated in FIG. 7 and FIG. 8, each ofwhich is described above. Preferred species of domed shapes includesemi-sphere and oval section dome. Other preferred formed shapes includevertically-oriented cylinder with a flat top, vertically-orientedcylinder with a domed top, conic-shaped side walls with flat top ordomed top, rectangular, cubic, horizontally-oriented cylinder section,and horizontally-oriented oval cross-section cylinder section, as wellas wavy cylinder sections.

Of course, in the inflatable article made according to the process ofFIG. 8, the films are also formed in the regions corresponding with thelocations of the connecting channels, the inflation channels, and theopen skirt or closed inflation manifold. A preferred shape for the filmregions which correspond with the formed connecting channels and formedinflation manifold is a semi-cylinder shape in which the cylinder ishalved in a plane including the central axis of the cylinder, with thecylinder being on its side, i.e., the axis of the cylinder beingparallel to the lay-flat plane of the film. The open skirt can be formedin any manner which keeps the skirt away from the heat sealing rollerduring the heat sealing step as illustrated in FIG. 8. Of course, if theprocess used to make the inflatable article is a process as illustratedin FIG. 7, the film regions which correspond with the inflation manifoldor open skirt need not be formed, as the locations of the raisedsurfaces of the raised surface roller (rather than the location of theunformed area) determine the locations which are heat sealed together.

If desired, various additives are also included with the films. Forexample, additives comprise pigments, colorants, fillers, antioxidants,flame retardants, anti-bacterial agents, anti-static agents,stabilizers, fragrances, odor masking agents, anti-blocking agents, slipagents, and the like. Thus, the present invention encompasses employingsuitable film constituents.

Although the inflatable article is made by sealing two outer film layersto one another, if the film cross-section is symmetrical with respect tolayer composition, as is preferred, both outer layers are hereinreferred to as “seal layers”, even though only one of the layers is notheat sealed to the other film making up the inflatable article. If theseal layers make up the majority of the overall film weight, the seallayers are present for more purposes than just sealing. The seal layerscan provide much of the strength, bulk, abuse, abrasion, and impactstrength properties for the inflatable article. Preferably the crosssection of the multilayer film is symmetrical with respect to layerarrangement, layer thickness, and layer composition.

Providing the film(s) with a gas barrier layer results in an inflatedcushioning product having a longer life under load, as the gas barrierlayer allows the inflated cushioning article to retain gas in the cellsfor a longer period of time while the cells are under load. This isimportant because without a gas barrier layer, the cushioning productunder load can exhibit substantial loss of fluid, i.e., “creep”, in, forexample, four to seven days. Suitable resins for use in the gas barrierlayer include hydrolyzed ethylene/vinyl acetate copolymer (designated bythe abbreviations “EVOH” and “HEVA”, and also referred to as“ethylene/vinyl alcohol copolymer”, and “saponified ethylene/vinylacetate copolymer”), polyvinylidene chloride (including vinylidenechloride/vinyl chloride copolymer “PVDC-VC”, and vinylidenechloride/methyl acrylate copolymer “PVDC-MA”), polyacrylonitrile,polyester (including polyalkylene carbonate), polyamide, etc., as knownto those of skill in the art. A particularly preferred gas barrier layeris made from 100% CAPLON® B100WP polyamide 6 having a viscosity ofFav=100, obtained from Allied Chemical.

If the film(s) are multilayer films having one or more seal layers and abarrier layer, it is likely that the polymer of the seal layer(s) doesnot bond strongly to the polymer of the barrier layer. The solution tothis problem is to provide the film with a tie layer between each seallayer and the barrier layer. As used herein, the phrase “tie layer”refers to any internal layer having the primary purpose of adhering twolayers to one another. A tie layer contains a polymer capable ofcovalent bonding to polar polymers such as polyamide and ethylene/vinylalcohol copolymer, as well as being able to bond to, for example,polyolefins such a polyethylene and ethylene/alpha-olefin copolymers. Atie layer can serve to provide a strong bond to both the seal layer andthe gas barrier layer. The tie layer can comprise any polymer having apolar group thereon (particularly a carbonyl group), or any otherpolymer which provides sufficient interlayer adhesion to adjacent layerswhich comprise polymers which do not adequately adhere to one another.Such polymers include olefin/unsaturated ester copolymer,olefin/unsaturated acid copolymer, and anhydride modified olefinpolymers and copolymers, e.g., in which the anhydride is grafted ontothe olefin polymer or copolymer. More particularly, polymers for use intie layers include anhydride modified polyolefin, anhydride modifiedethylene/alpha-olefin copolymer, ethylene/vinyl acetate copolymer,ethylene/butylacrylate copolymer, ethylene/methyl methacrylatecopolymer, ethylene/acrylic acid copolymer, ethylene/methacrylic acidcopolymer, and polyurethane. Modified polymers suitable for use as tielayers are described in U.S. Pat. No. 3,873,643, to Wu et al, entitled“Graft Copolymers of Polyolefins and Cyclic acid and acid anhydridemonomers”; U.S. Pat. No. 4,087,587, to Shida, et al, entitled “AdhesiveBlends”; and U.S. Pat. No. 4,394,485, to Adur, entitled “Four ComponentAdhesive Blends and Composite Structures”, each of which are herebyincorporated, in their entirety, by reference thereto.

Preferred polymers for use in the tie layer include olefin polymerswhich are modified (e.g., grafted) with one or more monomers such asacrylic acid, methacrylic acid, fumaric acid, maleic acid, maleicanhydride, 4-methyl cyclohex-4-ene-1,2-dicarboxylic acid anhydride,bicyclo(2.2.2)oct-5-ene-2,3-dicarboxylic acid anhydride,1,2,3,4,5,8,9,10-octahydronaphthalene-2,3-dicarboxylic acid anhydride,2-oxa-1,3-diketospiro(4.4)non-7-ene, bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride, maleopimaric acid,tetrahydrophthalic anhydride,x-methylbicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride,x-methylnorbom-5-ene-2,3-dicarboxylic acid anhydride,norborn-5-ene-2,3-dicarboxylic acid anhydride, Nadic anhydride, methylNadic anhydride, Himic anhydride, methyl Himic anhydride and other fusedring monomers, as known to those of skill in the art.

In the inflatable cellular cushioning article of the present invention,the tie layer can provides a high level of adhesive and cohesivestrength in order to prevent the multilayer film from delaminating whenthe article is inflated to an internal pressure of 3 psi under standardconditions (i.e., 25° C. and 1 atmosphere pressure), and thereaftersubjected to harsh conditions, for example, 140° F. for 4 hours. Notjust any tie layer polymer is capable of providing a level of adhesiveand cohesive strength adequate to provide the 3 psi inflated articlewith the desired performance properties when subjected to harshconditions. More particularly, a tie layer made of 100 percent anhydridegrafted low density polyethylene having an anhydride content of at least160 parts per million based on resin weight (as measured by pyrolysisGC-MS), preferably about 190 parts per million, exhibits a level ofadhesive and/or cohesive strength to prevent the article, when inflatedto 3 psi, from delaminating under harsh conditions. Preferably, themodified polyolefin is selected from modified LLDPE, modified LDPE,modified VLDPE, and modified homogeneous ethylene/alpha-olefincopolymer.

Preferred polymers for use in the seal layer include homogeneousethylene/alpha-olefin copolymer, heterogeneous ethylene/alpha-olefincopolymer (such as very low density polyethylene and linear low densitypolyethylene), ethylene homopolymer (low density polyethylene and highdensity polyethylene), ethylene unsaturated ester copolymer (e.g.,ethylene vinyl acetate copolymer, ethylene butyl acrylate copolymer,etc), ionomer resin, and polyamide.

EXAMPLE

An inflatable article in accordance with the present invention wasprepared in a manner similar to the process illustrated in FIG. 5,discussed above, with the exception that forming was not carried out ina fully integrated process as illustrated in FIG. 5. Rather, two flatfilms were extruded from two slot dies, respectively. Each film was amultilayer film having a thickness of 1.5 mils, each film having asymmetrical A/B/C/B/A layer arrangement, symmetrical layer composition,and symmetrical layer thicknesses. Each of the films had a unit weightof 38 grams per square meter. The layer arrangements, thicknesses, andcompositions were as follows:

TABLE I Thickness of Each Layer (% Layer of Total Film IdentityThickness Layer Composition A 43 Blend of 45 wt % HCX002 linear low SealLayer density polyethylene, 45 wt. % LF10218 low density polyethylene,and 10% by weight SLX9103 metallocene-catalyzed ethylene/alpha-olefincopolymer B 2 100 wt. Percent Plexar ® PX3236 anhydride Tie layermodified linear low density polyethylene copolymer C 10 100% Caplon ®B100WP polyamide 6 Barrier LayerThe flat films were cooled and thereafter heat sealed together by beingpassed in partial wrap around a raised surface roller in the mannerillustrated by FIG. 5. The raised surface roller heat sealed the twofilms together in a pattern providing 7 cells connected in series by 6connecting channels (i.e., one connecting channel between each pair ofadjacent cells) having a width of about 9/16 inch and a length of about3/16 inch. Each of the cells had a diameter of about 1¾ inches. Aninflation channel having a length of about ¾ inch and a width of about9/16 inch connected the open skirt to the proximate cell. The open skirtwas formed by flaps of film each having a width of ⅞ inch. Each cell wascircular in shape and had a diameter of about 1.75 inches.

A 3¼-inch long piece of the resulting uninflated, unformed, inflatablearticle 100 was cut from the roll, the piece extending across the full15½ inch width of the inflatable article. The 3¼-inch long piece of theinflatable article had one chamber running down the middle thereof.

Each of the 7 cell regions was individually heated, i.e., one at a time,for about 5 seconds with air at 240° F., using a from a Steinel HG 3002LCD heat gun, obtained from Steinel America, Inc., 9051 Lyndale AvenueSouth, Bloomington, Minn. 55423.

Immediately after the heating of each of the cell regions, the resultinghot portion of the article was placed in the press portion of a MullenTester, obtained from B.R. Perkins & Son, Inc., of Holyoke, Mass. Thepress portion of the Mullen tester was used to press the hot portion ofboth of the films to form a dome-shaped region having a diameter of oneinch and a height of approximately ⅜ inch. Both films were formedsimultaneously without trapping air between the films, and without anyfusion of the films in the formed areas. Each of the 7 cell regions ofthe films was formed in this manner.

After each of the cell regions were formed as described above, theresulting formed inflatable article 10 was inflated to an internalpressure of 3 psi, and a heat seal was made across the inflation channelto seal the chamber closed and entrap the air, under pressure, withinthe closed chamber. The inflated cells exhibited a total thickness ofabout 1 inch.

A measurement across the width of the formed, inflated article revealedthat the width of the inflated article was about 13⅜ inches, i.e., awidth reduction upon inflation of from 15½ inches to 13⅜ inches, whichwas a width reduction of only about 13.5 percent. A comparative sampleof the unformed, uninflated inflatable chamber 10 was inflated to about3 psi. The comparative inflated chamber was sealed closed at 3 psi, andwhen measured revealed a width reduction of from about 15½ inches to 10¾inches, i.e., a width reduction upon inflation of about 31 percent.

Thus, in the inflatable article according to the invention, thereduction in width contraction upon inflation appeared to be due to theforming of the cell regions of the films. It is believed that if theforming is carried out throughout the entire cell region, and if bothfilms are formed to a dome height of about ½ inch, the width reductionupon inflation to a pressure of about 3 psi will be very low, i.e.,close to 0 percent. Moreover, the height of the inflated cells in theformed inflatable article 10 was about 25% higher than the height of thecells in the inflated comparative sample.

In the figures and specification, there have been disclosed preferredembodiments of the invention. All sub-ranges of all ranges disclosed areincluded in the invention and are hereby expressly disclosed. Thoseskilled in the art will appreciate that numerous changes andmodifications may be made to the embodiments described herein, and thatsuch changes and modifications may be made without departing from thespirit of the invention.

1. An inflatable article comprising a first film bonded to a second filmso as to provide between the first film and the second film a pluralityof inflatable chambers comprising a plurality of cells, with each of thecells in the chambers being connected to at least one adjacent cell byan inflatable connecting channel, the first film being bonded to thesecond film between adjacent inflatable chambers, the first film and thesecond film each having a plurality of formed regions, the formedregions corresponding with locations of the cells and locations of theconnecting channels, with each of the formed regions of the second filmbeing nested into each of the formed regions of the first film.
 2. Theinflatable article according to claim 1, wherein each of the formedregions of each of the cells is surrounded by an unformed, unbondedregion of the film for enveloping a single inflatable cell.
 3. Theinflatable article according to claim 1, wherein the inflatable chambersextend transversely across the inflatable article.
 4. The inflatablearticle according to claim 1, wherein the first film is bonded to thesecond film with a heat seal.
 5. The inflatable article according toclaim 1, wherein the first film has a unit weight of from 20 to 250grams per square meter and the second film has a unit weight of from 20to 250 grams per square meter.
 6. The inflatable article according toclaim 1, wherein the formed regions in the first film and the secondfilm have a maximum dimension of from 0.25 to 3 inches.
 7. Theinflatable article according to claim 1, wherein the first film has aunit weight of from 60 to 250 grams per square meter and the second filmhas a unit weight of from 60 to 250 grams per square meter, and theformed regions in the first film and the second film have a maximumdimension of from 0.5 to 6 inches.
 8. The inflatable article accordingto claim 1, wherein the formed regions in the first film have a heightof from about 1 millimeter to about 50 millimeters, and the formedregions in the second film and the second film have a height of fromabout 1 millimeter to about 50 millimeters.
 9. The inflatable articleaccording to claim 1, wherein the first film has a thickness of fromabout 0.5 to about 6 mils and the second film has a thickness of fromabout 0.5 to about 6 mils.
 10. The inflatable article according to claim1, further comprising an open inflation skirt along a first edge runningthe length of the article.
 11. The inflatable article according to claim1, further comprising a closed inflation manifold running the length ofthe article.
 12. The inflatable article according to claim 11, whereinthe closed inflation manifold extends along a first edge of theinflatable article, with the plurality of inflatable chambers extendingfrom the inflation manifold across the inflatable article.
 13. Theinflatable article according to claim 11, wherein a plurality ofinflatable chambers extends from a first side of the inflation manifoldand a plurality of inflatable chambers extends from a second side of theinflation manifold, with the inflatable chambers which extend from thefirst side of the inflation manifold extending across the inflatablearticle towards a first side edge of the inflatable article, and theinflatable chambers which extend from the second side of the inflationmanifold extending across the inflatable article towards a second sideedge of the inflatable article.
 14. The inflatable article according toclaim 1, wherein each of the inflatable chambers contains from 3 to 20cells.
 15. The inflatable cellular cushioning article according to claim1, wherein the first and second films are connected to one another alongone fold line.
 16. The inflatable cellular cushioning article accordingto claim 1, wherein the first and second films are connected to oneanother along two fold lines.
 17. The inflatable cellular cushioningarticle according to claim 1, wherein the first film and second film areseparate films.
 18. The inflatable cushioning article according to claim1, wherein the bond is a heat seal.
 19. The inflatable cellularcushioning article according to claim 1, wherein the first film is amultilayer film and the second film is a multilayer film.
 20. Theinflatable cellular cushioning article according to claim 19, whereinthe first film comprises a seal layer and an O₂-barrier layer, and thesecond film comprises a seal layer and an O₂-barrier layer.
 21. Theinflatable cellular cushioning article according to claim 20, wherein:the first film comprises first and second outer layers, a central gasbarrier layer, a first tie layer between the first outer layer and thegas barrier layer, and a second tie layer between the gas barrier layerand the second outer layer; and the second film comprises first andsecond outer layers, a central gas barrier layer, a first tie layerbetween the first outer layer and the gas barrier layer, and a secondtie layer between the gas barrier layer and the second outer layer; andwherein the first outer layer of the first film is sealed to the firstouter layer of the second film.